This invention relates to sealing rings of resiliently compressible elastomers for use in sealing two members secured together with the ring interposed therebetween. More particularly, the sealing rings are used in equipment that generates high positive pressure, for example, compressors, or high negative pressure, for example, vacuum pumps.
In the prior art it has been customary to provide an annular ring of circular cross section, which is inserted into an annular recess in one member with a second member then brought into contact with the O-ring, such that the O-ring provides an annular seal between the two members. This O-ring projects above the recess; however, the portion retained within the recess does not fill this recess, because the circular cross section of the ring does not match the cross section of the recess, which is normally rectangular. The prior art has disclosed cross sectional configurations of O-rings of many varied shapes, having cross sections which do not fill their respective annular grooves. When an O-ring does not fill the recess, high positive pressure or high negative pressure will force the O-ring into the recess, causing it to collapse and permitting gaps to exist between the members to be sealed. These gaps, even when small, cause loss of efficiency due to loss of pressure or vacuum. When equipment is old and the members may be fatigued, warps in the members' surfaces and other distortions may occur, which creates variable spacing between the two members and results in gaps. These gaps result from the O-rings being compressed into the recess as the facing members are tightened in an attempt to gain a better seal between the warped members. In such cases it is even more critical that the sealing ring remains stable, has additional material extending above the recess and resists crushing into the recess.